Donald Trump has now shown the world the drawbacks of having an executive trained in business ascend to the Oval Office. It’s not the first time this has happened.

The 2002 class of Presidential Medal of Freedom recipients chosen by George W. Bush included many transcendent luminaries – among them Hank Aaron, Katharine Graham, and Nancy Reagan – and one now-tarnished star: Bill Cosby. Another honoree was 92-year-old management guru Peter Drucker, whose theories about corporations and leadership helped shaped Bush’s own approach to politics and the private sector.

The job of corporate CEO and U.S. presidency are American inventions, as Drucker once noted, and many voters have long harbored hopes that the skills of one might translate to the other. Specifically, some Americans yearn for a chief executive who could “run government like a business.” In George W. Bush, the country finally had somebody with training in both fields.

“He’s the first president to be an MBA, a Harvard MBA,” White House political adviser Karl Rove noted. “I had read Peter Drucker, but I had never seen Peter Drucker in action until I saw George W. Bush as governor of Texas.”

A naturalized U.S. citizen who left Germany in the 1930s, Drucker wrote three dozen books and thousands of columns and articles. He’s best known for foreseeing the knowledge economy, extolling decentralized decision-making, and encouraging corporations to view employees as assets. His most famous doctrine has been distilled into a mantra touted by several Republican presidents and management experts all over the world. Ronald Reagan summed it up this way: “Surround yourself with the best people you can find, delegate authority, and don’t interfere.”

This sounds straightforward in theory, but it’s tricky in practice. Appointing “the best people” is a subjective undertaking. And the difference between avoiding micromanaging and being inattentive to the point of abdicating responsibility turns out to be a fine line. These lessons were learned by Reagan in the Iran-contra scandal and by George W. Bush in Iraq. Two years after receiving the Medal of Freedom, Drucker was referring to “the tragedy of Iraq,” a war he considered “a total disaster.”

Forty years before the 2003 U.S. invasion, Drucker espoused a theory of management that might not have precluded U.S. military involvement in Iraq, but might have ended it much sooner. “Every product and every activity of business begins to obsolesce as soon as it is started,” he wrote in a seminal 1963 Harvard Business Review piece. “Every product, every operation, and every activity of a business should, therefore, be put on trial for its life every two or three years.”

“One question,” Drucker continued, “should be asked of each: ‘If we were not in this already, would we now go into it?’ And if the answer is ‘no,’ the next question should be: ‘How do we get out and how fast?’”

Barack Obama never mentioned Peter Drucker’s management theories while president. Nonetheless, a Drucker-esque reappraisal is what Obama undertook when it came to Iraq policy. Obama’s answer to the question “How do wet get out and how fast?” turned out to be: not too long. A month after taking office, President Obama announced plans to adhere to the existing U.S.-Iraq timetable of withdrawing American forces at the end of 2011. In August 2011, he rejected plans that would have kept up to 10,000 U.S. troops there, and never seriously negotiated an agreement with Iraqi leaders that would have kept them there longer. These decisions were controversial, but not a surprise. Obama emerged from the Democrats’ 2008 presidential field because of his opposition to Bush’s Iraq policy, and he ran against the war during the campaign.

Now comes Donald Trump, a president making a similar reversal of field. This one regards opposition to Obama’s Iran policy, which Trump excoriated while campaigning himself in 2016. What these two decisions show is the limits to Drucker’s philosophy and the fallacy of conservatives’ fantasy of running government like a business.

It seems self-evident to a majority of Americans that invading Iraq in 2003 was a catastrophic mistake. But pulling out of Iraq in 2011 was also a misjudgment. Yes, both perceptions can be true: Bush’s action destabilized the entire Middle East, squandered international goodwill toward America after 9/11, and all but consumed his presidency. Yet Obama’s precipitous withdrawal exacerbated regional disruption, led to yet more human suffering, and gave rise to ISIS.

The conduct of foreign policy, as it happens, has little in common with running a business. Making war is not the same as making widgets. Sometimes in international affairs, as in life, you look back on a decision, see in hindsight that you erred – but realize that you must nonetheless stay the course. That should have been President Trump’s reluctant conclusion regarding the multi-national Iranian agreement forged by Obama Secretary of State John Kerry, the Iranian mullahs, and a host of European bureaucrats and elected officials.

Instead, Trump precipitously pulled the U.S. out of the pact last week. “The Iran deal is defective at its core,” he explained. The agreement lifted Western trade sanctions, ratified Iran’s nuclear energy aspirations – so long as they aren’t using that technology to build bombs – and required the U.S. to unfreeze some $50 billion in Iranian assets. So what is Trump’s beef? His main complaints are two-fold: first, that the mullahs are using the cash infusion to finance terrorists and militias that are spreading sectarian violence all over the Mideast. Also, that the anti-nuke inspection program is toothless, which is frightening because Iran remains implacably committed to Israel’s destruction.

These were Benjamin Netanyahu’s objections. Charles Schumer’s, too. This view is hardly an outlier. The Iran agreement, which was a treaty in everything but name only, wasn’t ratified by the U.S. Senate, which would have protected it from Trump’s caprice, for the simple reason that Obama never submitted it to the Senate. Why? Because it’s doubtful it would have attracted a majority of the vote, let alone the required two-thirds majority.

Trump’s view is that retaining this “terrible deal” is throwing good money after bad. But the Iranians already have the money – the Obama administration flew $1.7 billion of it in cash to the mullahs – and they ain’t giving it back. Also, economic sanctions lose their effectiveness in the absence of an international consensus. This time Trump really has alienated our European allies while weakening any leverage the West had over curbing Iran’s rush to nuclear weapons. How does this make America safer?

Clearly, Trump didn’t take the objections of British, French, and Germans leaders seriously. Partly this is the allies’ own fault. Trump called their bluff on the Paris climate change accord, a posturing pretention that disadvantaged the U.S. without tackling global warming in any serious way. The Iran deal is different. Walking away from this pact risks catastrophe while simultaneously alienating America’s friends in the world for no tangible benefit.

Obama and Trump – and perhaps even Peter Drucker, who died on Veterans Day in 2005 – were wrong to believe that a large organization can just walk away from its previous endeavors, even if they were ill-considered. The answer to what ails us isn’t running government like a business. The answer is better government. And the place to start is electing officials who have the wisdom and gravitas to adhere to a road taken by their predecessor – even if they’d have never embarked on it in the first place.